This invention relates to a spray coating device for coating a pipeline, and more particularly to a spray coating device for coating a pipeline as the spray coating device travels longitudinally along the pipeline.
Pipelines when buried in the ground normally have an outer protective coating from corrosion and other detrimental effects. Over a period of time, a coating degrades and it may be necessary or desirable to remove the old coating and apply a new protective coat to the pipeline. For replacement of the old coating, the pipeline is removed from the ground and the old coating removed. The surface of the pipeline is then cleaned for application of the new coating of protective material. Normally a crane is utilized to lift the pipeline out of the trench with the exposed pipeline supported on skids or the like to permit access to the entire outer surface of the pipeline. After coating of the pipeline, the pipeline is lowered within the trench and covered with a suitable material.
Various types of spray coating nozzles have been utilized heretofore and some have been mounted on spray coating devices which are supported on the pipeline and move longitudinally along the pipeline. Normally, a pair of arms or arcuate rings of a semicircular shape encircle the pipeline and spray nozzles are mounted on the arms for coating the pipeline. In some instances, a plurality of nozzles are secured to the arms and pivot back and forth along a desired arc for coating of the pipeline. In other instances, the nozzles are mounted on carriages which move back and forth in an arcuate direction along the arms for spraying the coating onto the exterior surface of the pipeline during such movement or travel. The carriages reverse direction at the ends of the arcuate arms.
For example, as shown in U.S. Pat. No. 5,207,833 dated May 4, 1993, a spray coating device has been provided for coating a pipeline with the device supported on the pipeline and traveling longitudinally along the pipeline. A yoke is mounted about the pipeline for encircling the pipeline and carriages having a spray gun or nozzle thereon are mounted for movement along the yoke. The yoke is formed of a pair of generally semicircular halves or yoke portions and a carriage is mounted on each of the semicircular yoke portions. Each carriage has a single spray nozzle or gun thereon and the nozzle is mounted for pivotal movement relative to the carriage. The carriages are driven by endless belts which are reversed at the ends of the arms for reciprocation of the carriages. Such an arrangement requires controls for reversing the direction of travel of the drive belts and also results in additional time for reversing of the drive belts.
U.S. Pat. No. 4,953,496 shows an apparatus for both cleaning and coating the exterior surface of a pipeline. A pair of arcuate rings are mounted on separate arms which are mounted for pivotal movement between an operating position on a pipeline and a position for the removal of the apparatus from the pipeline. Carriages which mount spray nozzles thereon travel back and forth along the rings on the arms. The arms in addition to supporting the rings also have rollers thereon which ride along the outer surface of the pipeline for centering of the spray apparatus on the pipeline. Various hoses or lines extend to the apparatus for supplying the spray materials and hydraulic fluid. A suitable crane is normally used for lifting the spray device onto the pipeline and removing the device from the pipeline.
It is desirable that a spray coating device be provided in which carriages are mounted for reciprocal movement along a pair of arcuate arms and driven by flexible endless members that operate continuously in a single direction without being reversed.
The present invention includes a self-propelled spray coating device for coating a pipeline which is supported on the pipeline and travels longitudinally along the pipeline. A pair of generally semicircular arms are mounted on opposed sides of the pipeline for encircling the pipeline with each arm having radially spaced inner and outer guides. A nozzle carriage is mounted on each arm for arcuate reciprocal movement over 180 degrees along the inner and outer guides. An endless drive member is mounted on each arm and extends along the length of the arcuate arm. A drive connection is provided between each carriage and the associated flexible endless drive member to connect the drive member in driving relation to the carriage. The drive connection is effective at the ends of the arm to transfer the driving force for the carriage between inner and outer runs of the endless drive member thereby to permit a continuous movement of the endless drive member in one direction for the entire travel cycle of the carriage. The flexible endless drive member preferably comprises a chain mounted on sprockets at the ends of the arm for continuous movement of the chain in one direction. Each carriage has rollers for traveling along the radially spaced inner and outer guides on the associated arm.
To center the spray coating device, a pair of opposed separate arms are pivotally mounted on the frame of the device and are pivoted between engaged and disengaged positions with the outer surface of the pipeline. Rollers on the arms contact the outer surface of the pipeline for centering of the spray coating device.
The spray coating apparatus includes a self-propelled support vehicle movable alongside the pipeline and carrying various elements and controls for supporting the spray coating operation and the hydraulic fluid operation. A telescoping boom is pivotally connected to the support vehicle and is utilized for lifting the spray coating device on and off the pipeline in addition to supporting lines for hydraulic fluid and for the spray coating material. An operator for the spray coating operation controls the operation from a control panel on the vehicle. A support frame on the ground is provided to support the spray coating device when removed from the pipeline.
Various coating materials may be utilized such as an epoxy resin material in two components which harden when blended and cured. When cured, a hard polymer or epoxy resin material is formed to provide a strong, hard, outer liner for the coating on the pipeline. A two component polyurethane coating may also be utilized.
The thickness of the coating may be determined primarily by the speed of the spray coating device along the pipeline, the speed of the carriages moving back and forth along the arms, and the amount of coating material discharged from the nozzles. A central control panel on the self-propelled vehicle traveling alongside the pipeline permits an operator to control the entire coating process. Two or three layers of the coating material are normally applied to the pipeline and may be obtained by a selected overlap of the layers.
It is an object of the invention to provide a spray coating apparatus for spray coating a pipeline and supported on the pipeline for longitudinal travel along the pipeline.
It is a further object of the invention to provide such a spray coating device in which spray gun carriages are mounted on opposite sides of the pipeline for travel along generally semicircular arms which encircle the pipeline.
It is a further object of the invention to provide a spray coating device in which the spray nozzle carriages are driven by endless drive members connected to the carriages so that the carriages are reciprocated in a continuous movement of the endless drive members in a single direction for the entire travel cycle of the carriages.
A further object is to provide a lightweight spray coating device including a pair of arcuate arms suspended from a support frame and having a pair of spray nozzle carriages on the arms which move back and forth along the arms for spraying a coating on the exterior surface of the pipeline in a minimum of time thereby to provide a minimum of operating parts at a substantially lighter weight than heretofore.
Another object of the invention is the provision of a support vehicle for the spray coating device which travels alongside the pipeline during the entire operation and has a telescoping boom for supporting hoses for the coating material and hydraulic fluid in addition to lifting the spray coating device on and off the pipeline.
Other objects, features, and advantages of the invention will be apparent from the following specification and drawings.